This application claims priority to foreign application Germany 101 06 199.4, filed Feb. 10, 2001.
The invention relates to a method by which nucleic acids are isolated at flow-through filtering devices which, for example, have pores. For the isolation, a liquid sample, containing the nucleic acids, is allowed to flow through the filter device, the nucleic acids being retained in or at the pores. Usually, the filtering devices are then washed and the nucleic acids are eluted for further use in the next step.
Known methods use ion exchangers, for example, as filtering devices. Under low-salt conditions, the nucleic acid molecules are bound. Elution takes place under high-salt conditions, which make the further use of the eluted nucleic acid molecules difficult or usually requires a dialysis to be interposed.
Likewise, the use of filter materials, based on silica, in conjunction with binding buffers, which contain chaotropic reagents, is known. The chaotropic reagents bring about specific binding of nucleic acids to the silica materials. Admittedly, it is possible to elute once again under low-salt conditions here. However, it is a disadvantage that the chaotropic reagents are relatively aggressive, so that the working up is not problem-free.
It is furthermore possible to use molecular sieves. The disadvantage here is that, during the elution, the nucleic acids cannot be sucked through the molecular sieve in the original filter device. Instead, they must be eluted on the side on which they entered the molecular sieve. This usually means an additional step and, accordingly, prolongs the working-up time.
It is therefore an object of the invention to provide a method with which the disadvantages named above can be avoided.